The present invention relates to an improvement in the structure for attaching magnets of a rotor for a synchronous motor of a permanent magnet type.
In the prior art permanent magnet type synchronous motor, a rotor is constructed in such a manner that an even number of permanent 1 magnet in the shape of a column having a sectorial wedge-shaped section as shown in FIG. 1 are adhered around a rotor shaft 2 with an adhesive and are secured by a fixed ring 3 around the outer periphery thereof as shown in FIG. 2. Although the above structure is effective in preventing the magnets from peeling off to outward, when adhesive force becomes weaker by insufficient adhesion or deterioration thereof, repeated start and/or stop of the motor causes inertia sufficient to make the magnets slide circumferentially on the rotor shaft 2. This presents a formidable problem because the motor is often incapacitated for use.